A few years after Bowen C. Dees became president of the Franklin Institute, his grandson William Marble became his after-hours eyes and ears.

"My father took much pleasure in taking my son and seeing firsthand how a child reacts" to exhibits at the Franklin, Mr. Dees' daughter, Sarah Dees Marble, said in an interview.

She said he loved the aspect of the Franklin, "that was hands-on and that interested children. Get them young, he said, and you keep them."

On June 15, Mr. Dees, 91, president of the Franklin Institute from 1970 until he retired in 1982, died of congestive heart failure at Redwood Terrace, a continuing care community in Escondido, Calif., where he resided.

It was during Mr. Dees' time that the Franklin reopened its 1954 heart exhibit, in which folks could walk into a giant replica of a beating human heart to watch how it worked.

"He was always interested in making ordinary people understand and appreciate the importance of science," his daughter said.

The heart was rebuilt, reopened in 1979, and is still beating, said Franklin spokeswoman Kat Stein.

In 1976, the Franklin parked a Boeing 707 at its back door, where it stayed a few years, which riled some of the institute's neighbors.

In 1975, a schoolteacher neighbor who lived about the length of a football field away from the proposed site told an Inquirer reporter:

"How many people want to walk out their front door and see a plane? I think it stinks, what they're proposing. I find it very offensive."

Another nearby neighbor called the proposal "grotesquely inappropriate."

But a third noted that the institute's back parking lot, where the 747 would be sited, was "where derelicts and vagrants gather at night to scavenge off the garbage from the museum's restaurant concession."

These days, said Stein, "we have an enclosed space in the back called Science Park" that offers "outdoor activities for families."

The park is closed at the moment, Stein said, and so are the Dumpsters.

Born in Batesville, Miss., Mr. Dees earned his bachelor's degree in 1937 from Mississippi College and his doctorate in physics from New York University in 1942.

From 1937 to 1943, he was a graduate assistant in the physics department at NYU, and from 1943-44 a physics professor at Mississippi College.

From 1944-45, he taught in the radar school at the Massachusetts Institute of Technology, and from 1945 to 1947, he was an assistant professor of physics at Rensselaer Polytechnic Institute.

In 1947 in Tokyo, Mr. Dees was a civilian physicist in the scientific and technical division of the headquarters of the Supreme Commander for the Allied Powers. When he left in 1951, he was division chief.

In Washington, he joined the National Science Foundation as program director for fellowships from 1951 to 1956, and was deputy assistant director for scientific personnel from 1956 to 1959, assistant director for planning from 1959 to 1963, and associate director from 1963 through 1967.

Mr. Dees went to the Franklin Institute in February 1970, from the University of Arizona, where he was provost for academic affairs.

Before he worked in Tokyo, his daughter said, Mr. Dees published the first of his two books, a textbook titled The Fundamentals of Physics.

In retirement, he wrote of his Tokyo experiences in The Allied Occupation and Japan's Economic Miracle: Building the Foundations of Japanese Science and Technology 1945-52.

Besides his daughter, Mr. Dees is survived by his wife, Dorothea; stepdaughter, Evelyn Chow; and grandson, William Marble. His first wife, Sarah Sanders Dees, died in 1999.

Humphrey Mortuary in Chula Vista, Calif., said that no funeral or memorial is planned. Donations can be sent to the Bowen C. and Sarah E. S. Dees Physics Fund, Mississippi College, Clinton, Miss., 39058.